The FireWire.RTM. serial bus architecture was originally developed by Apple Computer. The objectives that drove development of the FireWire serial bus were ease of use, high rate of data transfer, support for isochronous applications, very large memory mapped address space and others. The IEEE formalized the FireWire architecture in the IEEE 1394-1995 specification. This standard will be hereinafter referenced as the "IEEE 1394 standard" or just the "1394 standard." A description of the IEEE 1394 system architecture is provided in the book, "FireWire System Architecture : IEEE 1394" by Don Anderson and published by MindShare, Inc., 1998. Details regarding the IEEE 1394 standard can be found in the "IEEE 1394-1995," "IEEE 1394.A," and "IEEE 1394.B" specifications, the contents of which are herein incorporated by reference.
Texas Instruments and other companies presently have a variety of chip sets for IEEE 1394 applications. The chip sets are generally comprised of either separate chips that implement the link and PHY layers of the 1394 standard, or a single chip that implements both the link and PHY layers. The link layer generally performs packet formatting for data to be transferred to and from a locally coupled host system, while the PHY layer provides the physical interface to the serial bus.
The commercially available chip sets are generally hardwired solutions that promote easy integration into specific applications. However, once the chip sets are integrated into a product, for example a digital camera, problems uncovered in the link/PHY chip set may be expensive to remedy. Furthermore, improvements in and extensions to the 1394 standard may make the chip set obsolete. Therefore, a link/PHY circuit arrangement that addresses the above identified problems is desirable.